text:
What instrument can be used to check that constant attitude is maintained?
In Sporty’s training, the following question came:

One way to determine that you are maintaining a constant attitude
is to occasionally check:
A. The vertical speed indicator
B. The tachometer
C. The altimeter

My answer is A, but sporty’s app says I’m wrong and correct answer is C.
Could someone please confirm the right answer and explain why?

Since the original question says "One way", it's not surprising that more than one answer is supportable, therefore there's arguably is no "right" answer and there's grounds for voting to close this question as being unclear.  You might consider rephrasing to ask "Can someone explain why C might be considered a better answer?" or something like that.

What a strange question. One can fly at a constant attitude for a wide range of altitude and airspeed. Scanning any of these instruments alone will tell you nothing.

@Sanchises, and an equally strange comment... They definitely don’t tell you nothing:  Each instrument tells you something, and scanning them all provides the big picture.

@Michael Hall: But that big picture doesn't include the ATTITUDE of the plane.  I strongly suspect a misspelling here.

@jamesqf, it absolutely does!  Maybe not in fine increments, but if your altimeter is unwinding, VSI is pegged down and airspeed is rapidly increasing that tells you the big picture that your attitude is nose down.

And I suspected a misspelling at first, but attitude is in bold, so clearly it is intentional and the question is in reference to secondary instruments.

@Michael Which is why I said "alone". I never claimed that instrument scans are useless. Just that you can't derive your attitude from looking at just your altimeter. The "correct" answer to this question might lead you to conclude that pitch determines climb rate, which is emphatically false.

@sanchises, but you also said “nothing”.  Be careful when stating absolutes!  ;)

@Michael Always be careful when stating absolutes :)

I would have chosen D. Airspeed indicator.

@copper.hat Agree!

@copper.hat Or e) auto-pilot :)

The VSI is intentionally designed to present the climb or descent rate averaged over about seven seconds, while the altimeter is designed to have as little lag as possible.  Except for in gliders where the altimeter may stick due to the lack of vibration, the altimeter will actually indicate a climb or descent sooner than the vertical speed indicator.  However, what you really want to know as a guide to whether you are holding the proper pitch attitude for the power setting, is the vertical speed over the long term, i.e. over a time-scale of a minute or more.  Since the change in altitude represents the vertical speed integrated over time, the altimeter is superior to the VSI for this purpose, just as it is superior for indicating the very start of a climb or descent.  Plus, in a situation where you are trying to hold a specific cruising altitude, the altimeter has the added benefit of letting you know when you've successfully remediated an unwanted change in altitude, regardless of whether it was caused by an updraft or downdraft, or by a slight error in the pilot's choice of pitch attitude in relation to the power setting.
Of course your primary pitch reference, that you are checking almost constantly, is either the view of the aircraft's nose relative to the horizon, or the attitude indicator.  The lack of "attitude indicator" on the list of possible answers suggests that this question was asked in the context of flight in visual meteorological conditions-- or, less plausibly, in the context of "partial panel" flying with no functioning attitude indicator.
Clearly, the original question was only intended to apply to the case where the pilot's goal is to fly horizontally, and he or she
is attempting to make the control inputs that are needed to accomplish this, rather than to climb or descend at a constant rate, or execute some other maneuver.  Otherwise, the suggested answer is clearly wrong.  That's the joy of this sort of multiple-choice question-- often it seems that it was deemed too expensive to expend the amount of ink (or bits) that would be needed to really constrain the problem enough to make the suggested answer actually be the most correct one.  Don't sweat it, just "go with the flow" and try to figure out what the take-away lesson is supposed to be.
Here's a bit of "forbidden knowledge"-- trying to maintain an exactly constant altitude over the short term by instantly correcting for every updraft and downdraft is actually less efficient than keeping the airspeed and pitch attitude closer to constant.  This is addressed in the last paragraph of this related ASE answer.  However, traffic and airspace considerations sometimes make the latter style of flying impractical.

Will mark this one as an answer as, in addition to explaining points mentioned earlier, it addressed both intentions of level flying and climbing at a constant rate, which was my source of confusion. I'll definitely go with the flow. Lesson I learned here is that passing the FAA test is just the tiny beginning of a long learning journey! As a side note, I emailed Sporty's with a link to this discussion so they can comment or update this question to something more specific...not sure if I'll ever hear from them, but will update if I did. Great information in this thread!

And here is what Sporty's CFI said! I'll let you judge them :)
Hello and thank you for your message.
This particular review question is specific to the information found at 1:10 on the four fundamentals related to altitude control. It provides various examples of how you can monitor the altimeter to verify the current pitch attitude is set properly to hold an altitude.
So the best answer choice in this case per the video training is the C, altimeter.
However, yes, the VSI can also be used to verify.
Sporty's CFI Support Team

Multiple choice questions are rarely about picking the only correct answer but instead often challenge you to pick the most correct answer out of a choice of 2 or more potentially correct answers.
I think that is the case here. While the VSI may well indicate to you that you are climbing or descending, it is unreliable for monitoring as it will be affected by small fluctuations such as up/downdrafts and lags quite a bit behind actual control input.
The altimeter, on the other hand, is quite stable and does not fluctuate quite so readily. If you're scanning and over a period of a minute your altitude has increased by 100 ft you can be pretty sure you're climbing - in that time the VSI may have indicated a climb, a descent and another climb etc. If you had scanned it while in a short-lived descent you might be fooled into thinking the long term affect was a descent. It was not - you were climbing overall.

But the question asks about ATTitude, not ALTitude.  I can readily maintain constant altitude and rate of climb while having the plane in much different attitudes, as for instance when practicing flight at the edge of stall.

@jamesqf right, but given you're stabilized at a particular attitude/speed config you know you're maintaining that attitude by the lack of change of altitude (assuming speed remains constant)

@jamesqf, if you have practiced flight at the edge of stall then perhaps you have also practiced partial panel under the hood?  If not, you should... it would clarify what Jamiec is saying.

@MichaelHall You know when you wonder if you're talking absolute codswallop - that's me right now! If what ive said is a) true and b) not well worded/unclear please feel free to edit it!

@Jamiec, your answer is spot on, and interestingly is correct whether the question is for “attitude” or “altitude”!  (Although if I had to wager a guess you bit on altitude, am I right?)  There’s not a tremendous amount of context behind the question, but I think it is safe to assume it is in reference to partial panel instrument flying.  Because otherwise attitude is determine by looking out the window.  Or at your attitude indicator.

@Jamiec, isn’t it possible to have a constant aTTitude while climbing? In which case altimeter will be continuously turning and it will be hard to judge if it’s turning at a constant rate. In the same situation, the VSI needle will likely be stationary and pointing to the rate of climb. Does this make sense?

@Michael Hall: Yes, I have done that, which is why I don't see how this answer, or any of the multiple-choice answers, is actually correct.  I could use e.g. airspeed indicator AND altimeter to check for constant attitude, but I don't see how altimeter alone would work.

@jamesqf, but the word “alone” doesn’t appear in the question. And as jamiec points out, these kinds of questions often come down to picking the “most correct“ answer. The altimeter certainly provides feed back on your attitude. Especially if that attitude is unusual...

@MichaelHall --re "There’s not a tremendous amount of context behind the question, but I think it is safe to assume it is in reference to partial panel... flying. Because otherwise attitude is determine by looking out the window. Or at your attitude indicator."-- I would suggest that even in the context of VFR flying, you often want to select a pitch attitude that results in a roughly constant altitude, given whatever power setting you have chosen. I would suggest that the question and the suggested answer match this paradigm perfectly. Of course it also applies to partial panel flying too.

@bluephoton -- the original question was undoubtedly intended to only apply to the case where the pilot's intention was horizontal flight.  As to why it didn't actually say that-- well, you may have guessed that my opinion of this sort of multiple-choice question is rather low anyway, so nothing surprises me here.  Certainly there's wiggle room to point out this discrepancy in a well-crafted answer.

It looks like the Sporty's material is in line with the FAA's Instrument Flying Handbook. Chapter 7 describes basic maneuvers using analog instruments and it describes the attitude indicator as giving a "direct indication of pitch attitude", while the altimeter gives an indirect one (p. 7-3):

At constant power, any deviation from level flight (except in
turbulent air) is the result of a pitch change. Therefore, the
altimeter gives an indirect indication of the pitch attitude in level
flight, assuming constant power. Since the altitude should remain
constant when the airplane is in level flight, any deviation from the
desired altitude signals the need for a pitch change.

Exactly. That is where I originally got my concept and understanding of Primary & Secondary flight instruments. Though, my understanding was that the FAA recently decided to remove that method from testing in favor of the Control & Performance method. Although, I fly by the Control & Performance method, I still find the Primary & Secondary method a helpful tool when practicing partial panel.

Phew, this backs up what I felt I just knew from training. I was beginning to wonder if I was wrong.

This question sounds like it is a throwback from when the Primary  & Secondary method of Basic Attitude Instrument Flight was the preferred method of teaching and testing student pilots instead of the Control & Performance method. This assigned a role of Primary or Supporting to each instrument for each basic maneuver. Student pilots were required to memorize these roles for each instrument and each maneuver.
The Vertical Speed Indicator plays a minor role in Basic Attitude Instrument Flying. The VSI has a lag factor that makes it unsuitable for giving immediate feedback like a Variometer. In the Primary & Secondary method, the VSI is only in the primary role for constant rate climbs and descents. In the Control & Performance method, the VSI is solely a supporting and cross check instrument, only. It is never a primary instrument unless their is an issue with the Attitude Indicator.
Here is a chart for the Primary & Secondary method.

BASIC ATTITUDE INSTRUMENT FLIGHT
Control and Performance:
(Attitude + Power = Performance)
The Primary instruments for all maneuvers are the Attitude Indicator and the Tachometer/Manifold Pressure Gauge
Primary and Supporting/Secondary:
Any instrument that is not Primary for a maneuver is Supporting.
An Instrument can only be Primary for one aspect of a maneuver.
The Attitude Indicator is the Primary for all changes of, transitioning to, and/or establishing a maneuver except for changing airspeed in a turn.
The Attitude Indicator is the initial Primary Bank for transitioning to or establishing a standard rate turns. Then the Turn Coordinator becomes Primary Bank.
The Tachometer/Manifold Pressure Gauge is the Primary Power for all climbs and constant airspeed/vertical speed descents.
Airspeed Indicator is the Primary Power for all turns, all level flight, straight and level, and the constant rate descent.
The Altimeter is the Primary Pitch for all turns, all level flight, and straight and level flight, and changing airspeed in a turn.
The Heading Indicator is the Primary Bank for all Ascents, all Descents, all straight (without turns), and straight and level flight.
The Primary Power will always be either the Airspeed Indicator or the Tachometer/Manifold Pressure Gauge.
The Tachometer/Manifold Pressure Gauge is the Primary Power or the initial Primary for changing airspeed in a turn. Then the Airspeed Indicator becomes Primary Power.
Solely changing airspeed only is a variation of straight and level flight where airspeed is affected by Power and altitude is affected by Pitch.

Interesting, I used to teach both, I didn't realize the primary/secondary was no longer taught.

I think it's not a good question because it's not specific enough. According to the answer you a need to check altimeter occasionally to determine your attitude. But that's not the case in other than level flight. You can look at altimeter all you want during climb or descent and it will not give you a slightest clue about how shallow or how deep your nose is. It should be a little more specific.
If the question was about level flight it might be closer to truth. However, I would still discuss that VSI is a better instrument to maintain level flight than altimeter. I see VSI as a moving average trend indicator, if you are into stats a little bit. It will show you the change and the direction of the change in altitude way before the altimeter at level flight. You can see VSI as an error indicator. The second you see it moving in one direction try to minimize the error.  Try that and you will see instant improvement in your level flights.

The question is bunk.  You check you attitude with the attitude indicator (and turn coordinator).
Here’s a real-world explanation:
One can maintain a perfectly constant pitch attitude while entering a climb or descent.  Alternately, a pilot might need to vary pitch attitude in order to maintain a constant altitude.  Your attitude indicator (and turn coordinator) give you attitude information. Those instruments don’t tell you how well you are flying, i.e. maintaining altitude, heading, and airspeed.
Let’s say, for example, you are in the clouds with a perfectly level attitude indicator and you notice your altitude is decreasing. We’ll say it’s caused by a small, steady downdraft. In order to correct the altitude loss, you will need to add pitch and power. Once corrected, a new pitch/power setting will be used to offset the slight downdraft (for however long it lasts).
In level flight, you will always be scanning your altimeter and adjusting with pitch attitude and power - not the other way around!  In a climb or descent, it’s the same, however you will add the vertical speed indicator to your scan to verify your rate of climb/descent you desire.
In other words, the purpose of your scan is not to make sure that the airplane’s attitude isn’t changing - and I think that is what the poorly worded question implies.  Rather, your scan is there to verify that you are performing your flight correctly (maintaining altitude, heading, airspeed).
Good luck!


text:
Do any regional turboprop aircraft have leading edge high lift devices?
I'm currently working on an aircraft design project for a regional turboprop. I wanted to know if there are any regional TP's with leading-edge devices. It seems that a lot of them have deicing boots on the leading edge that make high lift devices difficult to install. Also maybe TPs just don't need the additional lift.

Neither the Dash 8 nor ATR families (which cover the bulk of regional TP market) do.
Your last two sentence pretty much summarizes it.  Some of the additional lift potential of a slatted wing is from the camber increase when the slat is extended, but most is from the ability of the wing to operate well beyond the normal stalling AOA of around 15-16 degrees, into the low-mid 20s.  You have to design your airframe to operate at very high pitch angles to exploit this.  I'm not sure that boots are a factor because there isn't really anything stopping a designer from installing boots on a slat (it's effectively a rubber air mattress glued on the LE with contact cement).
Jets use slats to improve safety margins at reference (approach) speeds (also lowering the reference speeds somewhat) with their more highly loaded, high speed wings (over 100 lbs/sqf, with supercritical airfoils that have poor stall characteristics - the 737 is in the 140 lb/sqf range). Turboprops operate with somewhat lower wing loadings (under 100 lbs/sqf - the Q400 is about 97 lb/sqf) and more gentle-stalling airfoils, and don't really need slats to achieve the mission objectives cost effectively.
None of the DeHavilland Canada products, even those designed for extreme STOL like the Caribou/Buffalo or Dash 7, have used slat systems.  It was preferred to use fixed leading edge cuffs (drooping LEs) and elaborate double slotted flaps (full span in some cases) to get the desired lift coefficients at "normal" approach deck angles.
The regional airliners like the Dash 8 are not designed for STOL operation in the first place (the Dash 8 is a redo of the STOL Dash 7, which was a marketing mistake, developed around a "stub runway" concept based on MLS that never materialized), so there even less of a need for them.

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sort: votes


text:
Is it incorrect to say that "passenger jets like to cruise at higher altitudes because there's less drag"?
I hear it stated quite often that aircraft like to fly high because there's less drag at higher altitudes.
$$ \text{Range} = \frac{V}{g} \frac{1}{\text{SFC}} \frac{L}{D} \ln \left( \frac{W_\text{initial}}{W_\text{final}} \right) \; . $$
Aside from SFC, it seems that none of the components of the range equation are altitude dependent. Lift/Drag should remain constant assuming the lift and drag coefficients remain constant. Therefore, is it incorrect to say that there is a benefit to range flying at a higher altitude due to decreased drag?
Another question is, does the lift/drag ratio of an aircraft increase somehow at  higher altitudes?

There's less drag at the same speed (and other things being equal, aside from altitude).
This is due to lower air density at higher altitude, which linearly affects drag. But just the same, it affects lift! You get less drag, but less lift too. If you want to fly level, you can't afford that: lift must be equal weight.
So what do you do to restore lift? You either fly faster, or increase angle of attack (AoA), or both. Either way, drag will roughly be the same.
Flying faster with the same drag is the benefit. However, sooner or later you'll hit the speed limit. (Most commonly for jets, this will be the Mach limit). From then on, you can only increase AoA.
Changing the AoA affects the L/D ratio. It may increase or decrease, depending on how the wing was designed. There is a certain AoA which will be the 'best'. If the jet was optimised for cruise, it will fly close to that angle.
Does it make any sense to fly even higher, where you have to increase AoA past the best L/D angle? It might, but not much. Primarily because you might squeeze a little better fuel consumption in colder air (that SFC component), so the optimum may be slightly higher. But flying at a higher-than-optimal AoA may be unstable by speed. (Which is manageable, but is another difficulty you don't want).
At some point, you will exhaust either the AoA, getting dangerously close to stall (while, remember, being at the speed limit at the same time - the so called 'coffin corner'), or thrust: it will keep reducing in thinner air, until it becomes lower than drag. That's your ceiling.

Ah yes, this all makes sense. To clarify, will an altitude be reached where the optimal cruise Mach for an aircraft will no longer provide enough lift at maximum L/D? Can this altitude be above the troposphere, and can flight planning put the plane above the troposphere to extend range? Thanks, this question has been on my mind.

@MichaelHall don't you mean less drag at the same TAS?  The drag at the same indicated a/s should be the same, the dynamic pressure being the same.

@RoryMcDonald most airliners already cruise above the troposphere except in the tropical lats where the trop is closer to 40000 ft. At mid latitudes it's in the low-mid 30s, and in the north in the 20s, and as low as the teens in the arctic in winter.

@MichaelHall, I'm not sure it would be a clarification, because it requires to introduce the concept of IAS. It doesn't normally appear in aerodynamic formulae: it exists for pilots.

@Rory, it depends on what you mean by "optimal cruise Mach". If you are climbing at the best AoA (L/D), you'll be flying faster and faster (in terms of 'normal' airspeed, TAS). Mach may be increasing still faster, because the air gets colder (thus the speed of sound drops). So eventually, as I said, one of two things will happen: you'll hit the Mach limit, or you'll run out of thrust. (You'll be increasing your thrust setting in the process, even though the absolute thrust and fuel consumption (per hour) won't be significantly changing).

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What is the purpose of air that passes through the engine core in a turbofan engine? Is it mainly to spin the fan rotor?
The majority of the air going through the bypass is producing most of the thrust and providing the air that cools the engine.
Does is also provide the pressurization and cooling/heating for the cabins?
What is the purpose of the air passing through the core? Is the objective to spin the fan rotor even though it still produces thrust? Does it provide air for any other purpose such as cooling?

Does this answer your question? How do jet engines work?

A turbofan is a turboprop with a direct drive fixed pitch prop with lots of extra blades and a shroud around it.  The core on the turbofan and the gas generator on the turboprop are more or less the same thing.  The fan does the same thing the propeller does.

@John K - Technically with the GTF, they're no longer Direct Drive. On the whole this is the case though.

Yes but a small number of the total so far.  But actually, even more like a turboprop.

The core is the Internal Combustion Engine - it has intake (of air), compression (of air), combustion (of the fuel/air mix), and exhaust (water vapor, CO2, air) that provides the motive force to rotate the turbine (N2) and provide perhaps 25% of the actual thrust of the whole engine when it exhausts out of the tailpipe.
From How Do Jet Engines Work? on this same forum, we get this diagram to aid us:

This core may also provide the motive force for electrical generators, hydraulic pumps, bleed air, ant-ice etc. (it would be inefficient and make no sense to get these from the fan air).
The thus driven turbine via it's shaft rotates the compressor blades at the front/intake of the core thereby completing a loop and making this cycle self sustaining as long as there's fuel to feed the engine.
The turbine rotation and the compressor rotation and the flow of air so induced also make the fan (bypass) part of the engine rotate (N1) through aerodynamic coupling. Thus the fan cannot function without the core, but the core can function without the fan.
So, yes, the objective is to drive the fan rotor, because the fan rotor by itself is not an engine and cannot self-rotate with purpose of producing thrust, but it is a device that can be driven by an engine  to produce thrust, around 75% of the total thrust of a typical combination.

a yes would have sufficed

" . . . .  even though it still produces thrust?" - this is what prompted the lengthier answer. I haven't understood this point, I guess.


text:
How is airspeed measured on supersonic aircraft?
Behind the shock wave air is subsonic, would that not cause an issue with the pitot tubes or any other sensor?

Related: https://physics.stackexchange.com/questions/160413/how-does-a-supersonic-flight-speedometer-work


text:
How do I choose the vertical tail's airfoil?
I'm designing a fixed wing UAV and I'm having some doubts about how to determinate the vertical tail airfoil. It's important to say that we've already sized this surface. And till this moment we're using the software XFLR5 for the analysis.

Normally, you would pick a symmetric airfoil. The thickness should be between 9% and 15% to find a good compromise between structural efficiency and maximum side force. Choose a thicker airfoil at the root, a thinner one at the tip and interpolate linearly between them.
Of course, for supersonic designs a thinner airfoil should be selected.
In some special cases a cambered vertical helped to improve flight characteristics, but this concerned mainly very powerful, single-engine propeller airplanes. I would expect your UAV is outside of this category.
Depending on the Reynolds number range of this vertical, a member of the Wortmann FX71-L series might be a good choice.


text:
Does ARINC 429 have any error correction methods?
I'm currently studying the application of ARINC 429, and have noticed that ARINC 429 doesn't have an error correction but an Error detection set in the parity bit (bit-32).
Are there any means for error correction within ARINC 429? If there is, how does it solve for failed data transfer between two systems?

There are no error correction methods defined a the base A429 layer. As you noticed, words with an incorrect parity bit are often simply ignored by a receiver.
At application level, additional logic usually takes place if a certain word has not been received for a sufficient amount of time. For example a flight control computer might assume that the angle of attack information is invalid if the AOA word has not been refreshed for X amount of milliseconds (either because of a parity error, or complete absence of the word on the bus).
However, there are ARINC protocols built on top of A429 that do have error recovery mechanisms.
For example ARINC-739 (which defines MCDU communication), defines an ACK/NAK mechanism so that the receiver system can ask the transmitting one to resend some information.
Similarly, Williamsburg protocol (also defined in A429) defines explicit ACK/NAK and retransmission in case of error.

You wouldn't correct the ARINC 429 label, but simply ignore that transmission and wait for the label to be resent again.
If the label isn't received properly within the defined period it would be considered timed out and the last valid label would no longer be used (timed out).


text:
What was the reason for replacing the non-smoking sign with a "no electronics" sign?
When reading the following comment on question "Why do lavatories in modern planes still have ash trays?":
Andra: November 05 2014 at 16:00

I have flown on an Embraer 195 where the no-smoking sign was replaced by a no-electronics sign

What is the reason for exchanging the non-smoking sign with a "Please Turn Off Electronic Devices" sign?
Of course Smoking is prohibited on all flights around the globe, so
the answer where the comment is, is untrue. But was this sign unnecessary
because everybody knows it's prohibited?

If you think that smoking is really prohibited on all flights worldwide then you might find a regional flight in sub-Saharan Africa to be an interesting experience :-)

The standard US safety briefing includes a warning that smoking is not allowed.  So that should make the sign unnecessary.  It certainly makes it unnecessary to have a lighted sign that can be turned on and off.  (I think you may still find some no-smoking placards at various places in the cabin.)

I did some searching on this and it's been discussed on some aviation forums (e.g. here). I couldn't find any 'official' sources from airlines or regulators but on the other hand there are a lot of comments and observations that seem to make sense.
A simple summary would be that it's a result of increased public awareness of airline smoking bans combined with a massive increase in the use of portable electronic devices (PEDs). That has made some airlines decide that it's more important to focus on passenger behaviour with PEDs rather than smoking. Wikipedia has an unsupported (citation needed) statement along those lines:

Due to the ubiquitous prohibition of in-flight smoking and the
  increasingly widespread use of electronic devices, the illuminated
  no-smoking signs have sometimes been re-purposed to inform passengers
  to switch devices off for take-off and landing. Where this is the
  case, the no-smoking sign is permanently printed on the overhead
  panels.

Smoking on aircraft has been banned by most (all?) airlines and regulators for some time now (since 1988 in the US, for example) and the number of people travelling by air has increased significantly over the same period (e.g. UK foreign travel trend here). That means that more and more people know that smoking isn't allowed on aircraft and probably by now that fact has been 'absorbed' at a cultural level, at least in Western countries.
In the last 10+ years the numbers of PEDs in use has increased massively and they were banned too. I guess that at some point some airlines decided that the 'rising' issue of PEDs was more important than the 'declining' issue of smoking, and started adapting their signs, briefings etc. accordingly.
It's interesting that you saw the sign on an Embraer 195, which is used for regional not long-haul flights (as far as I know). Possibly the airline decided that on shorter flights there's less risk of passengers getting desperate for a smoke. But I couldn't find any information on which airlines and aircraft have these signs; that's up to the airline to decide when it orders the aircraft interior.
Of course now the US allows the use of PEDs in all flight phases and that makes it very likely that other regulators will follow. At some point the only sign needed may be the seatbelt one.

They'll eventually come up with something else to change the sign to, I'm sure.

The indication lights can be switched off and on with a switch in the cockpit. It is overkill to have this infrastructure for the no-smoking sign, if smoking is never allowed during any phase of the flight. A simple sticker would do.
Nowadays the use of electronic devices is sometimes allowed, sometimes not. Therefore it makes sense to dedicate the cockpit switch and the indication lights to this function.
In future we might see more displays like this one in a A350:

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text:
How common are aprons made of bricks?
I found this topic on an external site, it's about a Boeing 737-4 damaged during engine run up at Sialkot international Airport (Pakistan): NL B734 Damaged During Engine Run Up (photos)
In the comments/discussion, people say that there is similar apron paving made of blocks at other major airports.

Are there any photos or verification of lose-block apron?

One comment says that London Heathrow has some, does somebody have any verification or Link?

Block paving is very common at airports. All over Heathrow and Gatwick. It works fine when its built correctly but if it's not maintained well then that happens.

http://www.sept.org/techpapers/330.pdf

Hong Kong International Airport represents the largest single airfield installation of interlocking concrete pavements. Since most of the airport is on reclaimed land, anticipated settlement required that flexible asphalt pavement be used instead of rigid concrete for runways. Concrete pavers also provide a more fuel-resistant surface than asphalt.

Source

See also

Concrete Block Paving
for Airfields
Airfield pavement design with concrete pavers
Evolution of Interlocking Concrete Pavements for Airfields
THE USE OF INTERLOCKING CONCRETE BLOCKS ON AN AIRCRAFT PAVEMENT IN AUSTRALIA

Can you provide any examples involving red gritty bricks?

That brick surface is so clean... if it wasn't for the giant plane there, I wouldn't believe it actually serviced planes!

authors: Евгений Новиков

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text:
Are both RVR and visibility minimum required for CAT I ILS?
Is it required to have both RVR and visibility to be more than minimum for ILS CAT 1 or one of them is acceptable. If both required which one has priority.

If RVR (which is both runway-specific and more precise) is available, then it is controlling. If not then visibility (single value for the airfield) is controlling.
For example, typical Cat I minimums might be 1800 RVR or 1/2 Statute Mile (when the runway has an ALSF-II approach lighting system). If the RVR is near 1800 for one runway, the visibility may be low enough at the sensor for the airport that the prevailing visibility is reported as 1/4 SM -- too low to allow you to fly the approach (Part 121 rules, at least). But with the RVR, since it's measured at your runway (and often, right next to the touchdown zone of your runway), you're legal to fly the approach, since that much visibility "right here" means you have an excellent chance of seeing the approach lights at your DA.
Also, for all ILS approaches below Cat I mins (Special Cat I, Cat II, Cat III), only RVR matters.  The difference between each of those mins (1600 for Special Cat I, 1200 for Cat II, 600 for Cat III) are too fine to be captured by a "prevailing visibility" sensor.


text:
How do the A320 flight controls reconfiguration laws work?
Can someone explain in simple terms the reconfiguration laws? I have hard time understanding ELAC, SEC, FAC Priorities in FCTL Architecture Diagram.


text:
How to calculate the the variation of Cl wrt the angle of defection of the elevator?
I've checked the lift requirements of the aircraft and selected an optimal airfoil and designed a wing with dimensions of MAC 47cm and semi-span of 163.2 cm and a airfoil S1223. The horizontal stabilizer has a MAC of 17.5cm and semi span of 50cm with NACA 0012.
How can I calculate the change in Cl of the elevator with respect to the angle of deflection of the elevator?


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How to estimate the ribs spacing?
I would like to know what is the general logic behind the choice of the rib spacing in the thin-walled load bearing structure of a straight or swept all-metal wing? Is it the global or local structural stability, or the skin waveness tolerance, or something else?

What do you mean by rib steps?  Rib spacing?

Yes, rib spacing

Try a thought experiment. What would happen if you removed all the ribs?  Now put just one back right in the middle.  Still no good?  Keep adding them back with equal spacing, until the result is tolerable.

All of the above.  Mostly it's to achieve conformity to the "mold line", the outer airfoil contour, for as much of the wing as possible, and for buckling resistance of the flattened tube that constitutes a monocoque wing.  The buckling resistance mostly means resistance to torsional buckling, the pure bending being absorbed by the main spar.
On a strut braced wing, you can have a single strut and use the skins to make the wing torsionally rigid, or have a strut both fore and aft do provide the torsional rigidity and do away with skins altogether and just cover the wing with fabric.
So you can have more ribs with thinner skins, or less ribs with thicker skins, and it's a juggling act the designer has to work out based on design objectives.  For example, the designer may prioritize airfoil conformity between ribs, and use heavier skins that will deform less under air loads, and take advantage of the ability to use fewer ribs to compensate (it's more than just loads - a designer may use thick skins just because they want to use machine countersunk rivets and a minimum thickness is required for them).
On transport airplanes, the upper and lower wing skins are so thick they are called "planks" and actually form the effective upper and lower spar caps of a box structure that spans the entire chord between leading edge and trailing edge, with a relatively small number of ribs to hold the planks apart and provide buckling resistance.
If I'm trying to build a wing as light as possible, I might use more ribs and thin skins to get the torsional rigidity I need and support air loads. Or as mentioned previously, I might brace my wing with lift struts front and rear and use very thin skins that only have to support air loads, or just fabric.


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Where in the cockpit of a fighter such as the F-22 or Su-57 is thrust vectoring controlled?
Does it use the stick? Pedals?

A long talk about F-22 controls by a test pilot: https://youtu.be/n068fel-W9I (the gist is that side-stick and pedals tell the computer what the pilot wants and the computer combines all the available control elements to achieve it).

It is controlled by the computer(s). The pilot moves the stick/throttle/rudder in a way to tell the computer(s) what he wishes to do.
The computer(s) move the relevant controls, including the engine nozzles.


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What are these two sticks on chart holders?
Many different airplanes feature two small sticks on both sides of chart holders. These can be moved within a limited range. I've heard different versions about their use and haven't found any documentation regarding them.

You aren't going to find any documentation from the Learjet 45 AFM or PM.  They allow the pilot with paper charts to adjust the angle of the chart so the pilot can read it easier while flying.  There is no other purpose for those extra "small sticks"

All the versions I've heard, including my own, agree that it's to increase the angle of the chart so that it can be seen better. However, I've heard different versions regarding how to use them. Some say that the sticks tilt toward the pilot and the card rests on them, or that the sticks lower toward the yoke and the entire chart holder is tilted

I would imagine the bolt at the top of the chart holder is tight enough to keep the chart at any angle.

That's a theory and it makes sense; however, the other one could also be valid since it works and even allows writing on the chart holder without it coming off. I've seen this specific model in many planes like MD, CRJ, ATR... Experienced pilots I've asked haven't been able to confirm it definitively and even they have doubts.

@MiguelHernández You wouldn't have the chart holder tilt and have legs prop the chart up, that would be redundant. It would make sense to have the holder tilt and the legs hold it up, forming a triangle. That's the same concept as the Boeing holder. Note too it tilts the light at the same time, avoiding the chart self-shadowing.


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Why should the fuel shutoff valve in a Zlin Z-142 not be set to both for takeoff?
The fuel shutoff valve in the Zlin Z-142 has four different positions: Off, Left, Right and Both (L+R).
In the POH, the procedures related to normal flight operations, suggest that during taxiing and takeoff the selector is on Right and to switch to Both 5 minutes after takeoff.
I was wondering: why is that the case? Why not starting with Both? And also, why is it not needed to switch to Left after taking off to balance the fuel?

Pls check put recent answer by @carpmat, if a source can be verified for the answer, I think it deserves to be the accepted answer instead of mine.

Section 4, part 4.10 of Zlin Z-142 POH presents a following caution:

Caution:
At 1.L position (LEFT) and fuel quantity drop in this tank below 30 l it is necessary to increase attention to the right control of the aircraft. At long time yawing - the ball of turn and bank indicator being out of the centre on the left side - limitation of the fuel supply can appear and be followed by irregularity of engine run.
In case of fuel pressure fluctuation or irregularity of engine run change over to 2.R (RIGHT)

This leads me to believe that the fuel system design is such, that the left tank is more susceptible to interruptions in fuel flow than the right tank. Since taxiing  often imposes high slip forces (while turning), and takeoff is a phase of flight with all sorts of "floating around" regardless of how skilled the pilot is, it is best to ensure the fuel source is as stable as possible. Note that selector position 2.R (RIGHT) is also commanded for approach, and is to remain there all the way to engine shutoff. This would support the theory of right tank being the most reliable source of fuel.
The POH also commands startup and subsequent procedures to be executed with tank selector in 2.R (RIGHT) position. In addition to the right tank being (probably) more reliable when it comes to fuel delivery, not changing the tank until later in flight would keep the fuel flow coming from one single source, and possible problems relating to this source would likely present themselves before lifting off. Should problems arise after liftoff, there is then the possibility to try the left and both positions of tank selector to troubleshoot (I did not check the POH for these procedures).
Depending on fuel system design, selecting both -position during ground maneuvers may lead to fuel transferring inadvertently to either tank due to turns and/or slanted ground. This would cause imbalance during takeoff, which would be, if nothing worse, uncomfortable. More importantly, as StephenS quite correctly pointed out, selecting both tanks for approach and landing might prove catastrophic if, for some reason, extended period of approach was flown in sideslip. This might lead to problems described in POH in a very critical phase of flight.
One should also keep in mind that having 30 l of fuel in left tank you most probably have about the same in right tank too. That would be 60 liters of fuel in total, which is quite a lot, about two hours of flight time (rough estimate). So this this fuelling condition reffed to in POH of Z-142 is present in very "normal" fuel loads, not just when running on fumes.
Common feature in all procedures in POH's generally is keeping thing as simple as possible (this actually is not entirely true, but that's how things should be). This may also be a reason to stick to one fuel selector position until in cruise.

I would also suspect crossfeed causing issues during maneuvering for arrival and departure, especially slips to landing. In cruise, as long as your turns are coordinated, crossfeed shouldn’t be much of a problem.

thank you @Jpe61! Regarding the fuel imbalance, do you think that they didn't provide any instruction to balance the fuel after taking off because just starting the engine, taxing and taking off won'take much of a difference or because you are supposed to fill the right tank more than the left one?

@lennox oddly enough my phone won't let me download the pdf, but IIRC POH mentiones maintaining the fuel balance by selecting appropriate tank. Start, taxi and takeoff will not cause significant imbalance even if they are performed from right tank only.

thank you, I didn't find it mentioned in the one I have but I'll check again! Thanks for your help

If the tanks are near the wing root minor fuel imbalances have negligible effect until it's over 5 gal or more.  My PL-2 homebuilt has all the fuel in wing tip tanks and is very sensitive to imbalance. I have to fill the right with 2 gal more than the left when solo to have no hands free roll tendency on departure, and I have to switch tanks frequently to keep roll trim. On the other hand, the deep narrow tanks can't un-port from sloshing, so there aren't any fuel selection limitations.

It is simply because in the Z142 the fuel pump is delivering more fuel to the engine than the required and this excessive fuel is transferred back always to the right tank. If during taxi/take off it is full and you would use the left one or both tanks, there would be a possibility to leak this excessive fuel out from the aircraft via the right overflow valve.

This is a good answer, and actually somewhat proves mine wrong, or at least severely incomplete. I would edit just a bit: the fuel pump delivering more than needed is not a special feature of this aircraft, but a very common arrangement. And: is there a source you can cite here for verification?


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How can speed and power be made independent in an airplane?
I heard a piece of information many years ago, and the more I think about it, the less it makes sense. It was like:

When airplanes what to raise altitude, they do not increase speed, but they increase power. It is like when going up a hill, you do not walk faster, you just push harder.

Now, I understand the statement at an intuitive level. I understand what it means for me to go up a hill, because I know what I feel.
But things are quite different with motorized vehicle in general, and maybe with airplanes in special.
My understanding is that the following equation is (relatively) true (at least as a principle):

power = rpm * torque

and my understanding is that

speed = rpm * coef

so in the end

power = f(speed)

or

speed = f-1(power)

where f is mostly (?!) multiplicative, or at least linear(-ish).
Now, how can be power increased, without increasing speed?
This statement comes to confirm that I miss some information, since the general knowledge defies my formulas :)

There are two parameters that an A/T can maintain, or try to attain: speed and thrust.
(I understand that thrust is power).

The only way I can explain it is like this (and I need some confirmation):
The (pilot) "asks" to increase the rpm (as a base parameter, speed and power being derived parameters). In vacuum, all the energy is used or increase RPM, so power and speed remain proportional. But in the real world, and especially during flight, a lot of the energy is used or lost in many places. So speed and power no longer remain proportional, the difference being lost (e,g, to friction).
Additionally, please provide a better explanation of what I just wrote. I am really interested to understand the basics of this topic.
Basic formulas are OK. (Complicated) Integrals and derivatives should be avoided please :)

Notes:

I am not (by far) a mechanical engineer whatsoever. As a hobby, I practice "mental" mechanical engineering - trying to understand how some things can be designed; or trying to understand how some things are implemented. My background is more related to electric / electronics, software, management.

In the example with a man climbing a hill, my explanation makes some sense (to me): I prepare to increase the speed by using more power, then I make a short break to rest the leg, and to move to the other leg, and then again use higher power and so on. It is mostly like a human-implemented PWM. This is how the speed can remain constant, while the power increases. But how does this work for the engines / airplanes?

I am quite sure that ultimately everything is related to how much fuel is burned in the unit of time. Unless I am wrong.

My knowledge about airplanes and flight are limited at best, even though I understand some principles.

I have in mind 2 examples: 1. a screw being screwed in a properly threaded hole; 2. The car moving on a road: as long as the gears do not change, and wheels do not slip, speed=rpm*coef, where coef depends especially on the gear details and wheel sizes.

In an aircraft in straight and level, unaccelerated flight, all of the forces of flight are balanced. Changing the pitch of the aircraft without changing any other control will cause a change in speed. Changing the power setting without changing any other control will change the aircraft’s propensity to climb or descend. Functionally, this means that if you increase your power in a plane that is trimmed out for a certain airspeed, the nose will rise and the plane will climb. If you decrease the power, the nose will fall and the plane will descend. In both cases, the airspeed remains constant.

@virolino Those examples are different because a screw and a car tire (at least usually) do not slip, meaning any motion of the tire directly translates to a motion of the car. When the tire starts slipping, this is no longer true. In an aircraft, the propeller kind of slips in the air all the time.

@Bianfable: "In an aircraft, the propeller kind of slips in the air all the time." - that is one of the basics, where I have intuition, but not explanation.

Also, your examples of a screw and a car are a little too simplistic to apply to aerodynamic forces. The propeller of an aircraft has aerodynamic forces acting on it. Several factors will affect it like density altitude for instance. For example, an aircraft on the ground with its brakes on will not increase its speed regardless of power setting or prop rpm. Also, power setting and prop rpm in a plane with adjustable props are linked, but not linearly/directly dependent on each other.

@DeanF.: I can understand the car dynamics relatively good (at least at a macro level). Basically, a car has a steering wheel which steers the front wheels to choose direction, and has 2 pedals to decide the RPM, and thus speed. However, the airplane is a totally different monster. I do not understand how everything fits together, and I hoped for a more "basic" explanation. I am not sure how to explain my level of understanding.

@DeanF.: you are right, a screw is a tad simpler than an airplane, I am aware of that :) But my level of knowledge and understanding is closer to the screw and car, and farther from the plane.

I just understood the kind of explanation that I need: airplane's speed and power for dummies :D   Disclaimer: I am the dummy ;)

Actually, you are little off on your understanding of cars as well. A car has one peddle to control power. The power tangentially controls the speed. You have to use a sufficiently large amount of power to accelerate. Once you are at your desired speed, you only have to use enough power to counter friction and drag. If I am cruising at highway speeds, friction and drag will eventually slow me down. On the other hand, I have a hill on my route home. To maintain constant speed, I have to increase power when reaching that hill. Just like an airplane.

@DeanF.: about the car pedals, you are right, I wrote stupid (even thought I actually have the good understanding). About going uphill -that is where I miss something. I use the same action (push the pedal) to modify either speed or power, right? How are they related? Or independent? (I ignore the trick of using the gear box for easier climb). (I drive a manual gearbox car, so the car does not change any gears for me).

Airplanes have two controls that control the thrust force of the prop-engine configuration. One controls the power generated by the engine. The other controls the prop angle. Airplane engines are fixed to their props either directly or by a fixed, non-adjustable gear set. The engine’s torque directly counters the air resistance of the spinning prop. The air resistance is determined by the prop angle setting. This, in turn, determines the RPMs of the prop. A combination of angle and rpm determines the amount of thrust force generated.

Also, a car’s engine rpm does not directly relate to its wheel’s rpm. There is a relation per gear chosen. Whether automatic or manual, the RPMs will change based on the gear selected. Regardless, the power is determined by the amount of fuel you meter out to the engine using the throttle. The less force that you need, the less fuel you meter. For instance, when traveling away from my house, I have to completely bring my engine to idle in order to go down the same hill without going too much over the speed limit. same with airplanes. And, I drive both automatic and manual transmission cars.

Let us continue this discussion in chat.

I throught (I am not a pilot) that: if a pilot adds power, but keeps the altitude constant, speed must increase; if a pilot adds power, but keeps the speed constant, the plane must rise.

@CGCampbell - You are entirely right (sort of). In order to keep the altitude constant when adding power, adjustments have to made in other controls to adjust attitude (pitch). If the only adjustment to the aircraft you make is in the throttle setting (power), the airplane will naturally seek a balance in the four fundamental forces of flight, resulting in a climb or descent. Speed will remain constant.

@CGCampbell, your intuition is spot on.  This really isn't a difficult concept, the OP is way overthinking this...

The problem is your assumption of

speed = rpm * coef

This is only true as long as there is a rigid connection between the RPM and the medium against which the speed is measured.
Let us consider a car for a moment. In a fixed gear, there is a fixed relationship between the engine RPM and the RPM at which the tires rotate. As long as the tires are not skidding, this will directly translate to a motion w.r.t. the road (against which speed is typically measured for a car). This results in the linear equation you show.
This is however not true for an airplane, where the propeller RPM does not directly translate to a speed w.r.t. the air because air is not a solid (otherwise it would be true and you can think of the propeller as a a screw that drives into the solid). Air can flow through the propeller without moving the plane. Consider e.g. a plane that is tied down on the ground and therefore cannot move w.r.t. the ground. You can still start the engine and run the propeller, which creates an airflow behind the propeller, but does not cause any movement. The same could not work with a car, as long as the tires are not allowed to skid.
In flight, the accelerated airflow behind the propeller creates thrust, which is a force that can accelerate the aircraft forwards. The actual motion will also depend on the aerodynamic forces (lift and drag) as well as gravity of course. A higher propeller RPM (at the same blade angle) will give you more thrust, but there is no rigid connection to speed.

Now, how can be power increased, without increasing speed?

Think of the airplane for a moment as a black box. It moves through air, creating a drag force. This drag force needs to be overcome by supplying a thrust force which works in opposite direction. Basic physics, equilibrium of forces, no integrals required.
Moving an object against a resistive force needs work $W$ to be done. For our black box aircraft, this work is the drag force $D$ times a distance $s$. Or the thrust force $T$ times $s$, because the forces have the same absolute value. So for unaccelerated, steady, horizontal flight we can calculate the work:
$$W = T\cdot s$$
Quick unit check: Drag and thrust are measured in Newton, which is a kilogram times meter per second squared in basic SI units, speed in meters per second and work is either measured in Joule, Watt-seconds or Newton-meters. Check.
Now the black box aircraft climbs. This needs additional work to be done on that aircraft, and if speed does not change, an additional term must be added. The work for lifting the mass $m$ by a height $h$ against Earth's gravitational acceleration $g$ comes on top:
$$W = T\cdot s + m\cdot g\cdot h$$
or, expressed in terms of thrust required:
$$T = D + m\cdot g\cdot \frac{h}{s} = D + m\cdot g\cdot \frac{v_z}{v}$$
where $v_z$ is vertical speed. Without vertical speed, we get the equilibrium for horizontal flight. Going up requires more thrust (positive $v_z$) and going down requires less (negative $v_z$) than in horizontal flight.
Power $P$ is the derivative of work over time:
$$P = D\cdot v + m\cdot g\cdot v_z$$
So the answer is: By varying vertical speed, you vary power while maintaining flight speed.
What that means technically for the propeller: It needs to accelerate the mass flow going through its disk more in order for the airplane to climb or less in order for it to sink. By changing engine torque, the pilot controls by how much that air is accelerated. In a fixed-prop airplane this means that the prop will spin at a different speed (faster for climbing, while flight speed is constant) and for variable-pitch propellers adding torque will increase the prop pitch so it will shovel more air past it per revolution (while keeping prop RPM and flight speed constant).

Regarding the question about raising altitude and increasing power, airplanes are no different from cars or people: To transfer from level movement to one that has a vertical component, you are going to need more power to maintain the same speed.
The need to increase power in all of the aforementioned cases comes from increasing the potential energy as we (with or without a vehicle) are gaining altitude. We are ascending in earths gravitational field, and to do this, we must do work. This work comes on top of the work we are doing to maintain speed.
There is no running away from gravity, so if we want to ascend, and do not increase the amount of work (power), there will be less work available for going forward, so we will slow down, and depending on climb gradient, come to a stop.
In the case of an airplane, slowing down will become problematic as staying in the air is dependent on speed. At some point the forward speed will not be sufficient for the wings to create lift, and the aircraft will stall and begin to fall from the sky.
Friction, air resistance (or drag), slipping of the tyres or propeller are basically a separate phenomena from the need to increase power to ascend.

To fully understand the answer you are striving to get, you have to understand the four fundamental forces of flight. These are best explained in the Pilots Handbook of Aeronautical Knowledge. It will explain more about the forces interaction. The ones you are most concerned with are thrust and drag. Thrust is a function of the engine-prop combination, not necessarily power alone.

Start by studying gliders -- note that while they cannot maintain a climb in the absence of updrafts, they can certainly be flown at a wide range of airspeeds, with no influence from a motor at all.
An airplane is nothing more than a glider with power added.  Fundamentally, the power setting governs the climb or descent rate for a given airspeed, but doesn't directly govern the airspeed.
Nor does the airspeed directly govern the power output.
In the simple case of a fixed-pitch prop, your suggestion that we can get more rpm and thus more power out of the engine by going faster is correct, but any suggestion that we generally ought to increase speed in order to climb would be incorrect, because it would completely overlook the increased drag that always comes with increased speed.
As for your intuitions based on going up a hill in a car--
Think about what happens when you downshift gears in a car.  RPM goes up and the engine can put out more power for a given forward speed.  Since the propeller is not rigidly connected to the air, there are two ways we can "downshift" in a propeller-powered airplane.

In an airplane with a simple fixed-pitched prop, simply advancing the throttle will cause the engine to turn faster for a given forward airspeed.  The fact that there is some "slipping" between the prop and the airstream is what allows the prop rpm to be increased without increasing the airspeed in this case.  And bear in mind that the pilot can always control the airspeed independently of the prop rpm, by pitching the nose up or down, or to put it another way, by adjusting the angle-of-attack of the wing.  The airplane may have its own "idea" of what "ought" to happen when the throttle is advanced, but the pilot can always override that inherent tendency and make it do something else.  Starting from level flight, if airspeed is held constant and the throttle is advanced, the aircraft must climb.

If the prop blade angle may be mechanically varied, then we also have the option of advancing the throttle and increasing the engine power output without any change in engine rpm or prop rpm.

Let's return to this idea for a moment--

The airplane may have its own "idea" of what "ought" to happen when
the throttle is advanced, but the pilot can always override that
inherent tendency and make it do something else.

Many people share the impression that if we move the throttle or power lever forward in an airplane, the natural tendency is for the aircraft's speed to increase.  Even if we understand that the prop rpm is not rigidly coupled to the airspeed, we still might think that there is some tendency in this direction, based on our experience in driving a car up a hill, etc.  In reality, the stability dynamics in an airplane are completely different from the dynamics of driving a car.  In many aircraft, advancing the throttle or power lever tends to cause the nose to pitch up so much that the airspeed actually decreases, if we don't do something with the control stick or control yoke to counteract this.  In other aircraft, advancing the throttle or power lever does tend to cause the airspeed to increase, if we don't do something with the control stick or control yoke to counteract this.  In all cases the pilot is free to override these tendencies and make the aircraft fly at the most desirable airspeed for the climb.  The airspeed he or she selects will vary depending on whether he or she wants to climb as steeply as possible or as quickly as possible, and the choice of airspeed will be accomplished by manipulating the elevators via the control stick or control yoke, not by adjusting the throttle or power lever.
Also, you said--

I am quite sure that ultimately everything is related to how much fuel
is burned in the unit of time. Unless I am wrong.

It all depends on what parameters we constrain to be constant.  It is certainly possible to burn more fuel per unit time flying horizontally than climbing.  But if we constrain the wing's angle-of-attack to be constant -- which for shallow to to moderate climb angles, is essentially the same thing as constraining the airspeed to be constant -- then the climb rate will end up being related to the fuel burn per unit time.
In these kinds of discussions, a key issue is what parameters are being held constant and what parameters are allowed to vary.  For example, if the pilot is holding the airspeed constant while varying the power setting, the results will be different than if the pilot is holding the pitch attitude constant while varying the power setting, but in neither case will the aircraft's natural pitch stability dynamics come into the picture.  If the pilot is varying the power setting while keeping his hands off the control yoke and making no changes to the elevator trim, then it's a different story, but likely not the one you are asking about.

In level flight if you increase power, speed will indeed rise.
If you are talking about rising the RPM with a constant speed propeller, the speed will only slightly change (because the engine may produce a different power output at a different RPM).
Changing RPM in a constant speed propeller does not produce great changes of power.
It's just like selecting a different gear in a manual transmission withouth changing the accelerator value.
Changing Manifold Pressure (the throttle lever) will.


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How can we define that an Engine or Airplane is ETOPS compliance?
What is the process for obtaining ETOPS certification for an engine or aircraft?

Are you asking about the definition of ETOPS compliance or "How can we find out that something is ETOPS compliant"?

The engine manufacturer must get the certification for this specific model.
The aircraft manufacturer must get the certification for this specific aircraft with this specific engine
The operator company must get itself the certification, particularly the maintenance team.
The operator having been certified must get the certification every aircraft apart.
Certification is 90 min or 120min or 180 min

You don't certify the aircraft or the engine in isolation. ETOPS requires the airframe/engine combination to be certified as a whole. The combination must first meet the basic type certification requirements, then the operator of the aircraft must comply with the registration authority's rules for ETOPS operation in the country of registration.

Hi Juan, thanks for the feedback, is there any terms or documentation by that we can said particular asset is ETOPS Certified ?

From the above explanation you can deduce that you need to check the type certificate and the particular aircraft. I think in some cases you also need to certify the aircraft and engine in combination with the crew, but that I am not sure how it works. I have read that in some countries crews that have already been certified and have ETOPS experience are signed off right away, and others require training (theoretical and practical) but don't quote me on that. :)

Thanks for such notes, will see and try to use this points in my required stuff :)

You're welcome. If you like my answer don't forget to mark it as the accepted answer. :)


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What is the reason for the T- shaped rudder trim tab on the DA42?
Why does the rudder trim tab on the DA42 have a T-shape?

I'm not sure it is clear what you are asking. What do you mean by "characteristic"?

I meant, aerodynamically what is the purpose of such design ?

Looks like you got your answer then. :)

The feature was added to reduce undesirable flutter discovered during flight test.  It appears on the rudder trim tab of the DA-62 as well.

"Buzz" (a simple vibration that doesn't excite sympathetic motion in the surface and structure) or just "vibration" might be a better word than flutter.  When you get flutter you generally don't survive it.  Another purpose of those kinds of TE add-ons (and the bulged surface itself) is to help with a dead zone problem that prevented the surface from precisely centering.


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How does forward sweep of a wing affect the formation of shock waves?
I understand that sweeping a wing back reduces the component of velocity perpendicular to the wing and can allow it to travel at subsonic conditions, and reduce the formation of shock waves, even if the freestream velocity is greater. I am wondering if the same concept applies for a forward swept wing or if there are other factors to take into consideration?

The same rules apply for the forward sweep. But care should be taken since multiple problems can arise. For the forward sweep wing an outer part of the wing can be outside the mach cone of the nose. Also a shock is forming at the wing tip which will influence the other half of the wing (this is a difference in the flow field to the backward swept wing and introduces an interaction of both sides). An Advantage of forward swept wings is, that it is easier to achieve a smooth Crossection Gradient Distribution over the airplane (lower wave drag).
This question is really nice! I was trying to find resources and couldn't find any! So any suggestions/corrections are welcome.

Thanks for your response! You mention that the shock is forming at the wing tip, I am wondering if, because of this opposing spanwise direction of flow that the shock is more important and difficult to control at the inner wing for forward sweep?

I don't think i am qualified enough to give you a correct answer. I think the spanwise direction of the flow is not really the  problem, but more the interaction of the shocks. It is probably more difficult to control the flow in the inner wing, but what is the advantage of that? Having the ailerons on the outer wing would suggest to me, that having forward swept wings is even advantagous for controlability (disregarding twist). But as mentioned in the beginning, this are just thoughts, and maybe somebody with the proper background can give you a more precise answer.

The forward swept wings  don't flying at supersonic speed, aerodynamic twist (and flutter) are two major issues. Straight wings can't go supersonic how can forward swept do it?

Incorrect; the X-29 had forward swept wings and a max speed of Mach 1.8.


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Why descent below DA/DH or MDA could only be accomplished using natural vision?
I'm curious why descent below DA/DH or MDA could only be accomplished in visual approach conditions? Is there any regulation to indicate that?

Are you asking about seeing the runway in general, or about it seeing with unaided vision? Before it was edited, your question seemed like you might be asking if synthetic vision, night vision goggles or other things would be acceptable? If so, there are indeed specific regulations on using them in place of unaided vision.

The FAA states it pretty explicitly in their definitions:

Decision Altitude (DA). A specified altitude in the precision approach at which a missed approach must be initiated if the required
  visual reference to continue the approach has not been established...

and similar for MDA

Minimum Descent Altitude (MDA). The lowest altitude, expressed in feet
  above mean sea level, to which descent is authorized on final approach
  or during circle-to-land maneuvering in execution of a standard
  instrument approach procedure where no electronic glide slope is
  provided.

To over simplify it a bit: As noted in the comments, ignoring the not in use CAT IIIC approaches the whole point of an instrument approach is to get you down to a specified point where you should be able to see the runway. If you can't, then the weather has degraded and you must either try again or go to an alternate. The big idea being that at some point you need to be able to see the runway in order to land on it. Depending on how precise the equipment you are using is (ILS, GPS, RNAV, VOR, (AFD dare we say)) the height you can get down to without being able to see the runway changes.
As for why there are minimums its likely historical, and at least in part practical. Not all approach systems/options take you right down to the threshold like say a circling approach and its possible to fly a poor approach that is within limits and not be directly in line with the runway when you pop out of the clouds. Thus you will need some time and distance to align visually, so minimums exist. On the historical side, early attempts at instrument landings systems we less than optimal to say the least and you would need time to pop out and align.

In addition to the precision of the guidance, there will be some cases where, if you proceed below your published minimums & then later realize that the visibility is insufficient for a safe landing, you may not have the required obstacle clearance during the missed approach.

The question asks why though, which I don't see addressed here?

Also, instrument approaches have some margin for pilot error, meaning even on a precision approach, you may not be lined up correctly. The pilot needs some time (i.e. altitude) to recognize and correct that before touching down. For non-precision approaches, you may be approaching from up to 180 degrees off the runway, which means a much larger (and usually much higher) obstacle clearance area.

Federal Aviation Regulation 91.175(c) discusses operating below the DA/MDA of an approach.  According to this regulation, in order to descend below the minimums for an approach:

we don't care about this.
we don't really care about this either.
At least one of the following visual references for the intended runway is distinctly visible and identifiable to the pilot...(goes on to list the references, essentially the runway, runway lights, and surrounding environment).

Thusly, we can see that (excluding CATII and III approaches, and approaches with an Electronic Flight Vision System [disccused in FAR 91.167]) it is legally required to have certain visual references in sight before descending below minimums. The required weather conditions, however, are often below what would be considered VMC (or true visual conditions).


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Static port and Bernoulli
Static ports open directly to the outside of fuselage. When aircraft is flying, there will be air flowing outside of static port. How does this not cause a vacuum effect inside the static port. Due to the Bernoulli Effect, as the speed of air flowing outside of fuselage increases, the pressure inside static port should decrease. This means, on same altitude, depending on my aircrafts speed, I will read different values on my altimeter. What prevents this ?

"Due to the Bernoulli Effect, as the speed of air flowing outside of fuselage increases, the pressure inside static port should decrease." Who told you that? That's not true.

When aircraft is flying, there will be air flowing outside of static port.

No, that is not true if the aircraft flies without sideslip and at constant altitude (which it should do most of the time). Instead, there will be a pressure equilibrium between the air in the lines leading to the static port and the static pressure outside. The position of static ports is carefully chosen so the airflow around them is neither accelerated (which would lower local static pressure) nor retarded (which would increase local static pressure). Also, static ports are on both sides of the fuselage so the ram effect of the windward static port in a sideslip is equalised by the suction on the leeward static port. Note that in this case there is indeed some air flowing from the windward to the leeward side through the static line connecting both.
Now to the Bernoulli effect. It says in essence that the sum of static and dynamic pressure is constant (if we disregard the height term, which is not needed in this context). Since you want to measure the same pressure that a stationary observer would measure, you need to pick a place along the airframe where the dynamic part of the pressure is zero because all flow is tangential to the port opening. Small errors can be corrected by calibrating measurements in flight test.

This is a really good question! The Bernoulli Effect requires a decrease in the size of the space through which air is traveling to obtain a decrease in pressure. Just having airflow moving past the static port will not induce the effect.
A static port is essentially just a small hole somewhere outside the aircraft that provides a source of ambient air pressure for instruments that use it to provide indications of altitude and rate of climb/descent for example.
Also, static ports are usually located on the side of the fuselage, where the boundary layer will provide a relative smooth airflow from where to sample that ambient air pressure.

Thanks for your answer. So you say, the air which flows outside the static port, does not cause a vacuum effect inside of static port tubes.

If the port is placed correctly on the aircraft's exterior, yes. If it caused a vacuum it would make any instruments read incorrectly. For example, on older aircraft you may find a venturi tube on the outside of the aircraft. The tube produces a decrease in air pressure in the middle from Bernoulli's effect that is used to drive gyroscopic instruments. Putting the static port there as well would make it useless.

Ok, Thanks. Can a relative wind couse this pressure to change ?

Not in my experience. Relative wind is more applicable to angle of attack than to something like this.


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As a drone hobbyist, is flying below the listed FAA UAS ceiling a violation of controlled airspace?
FAA (emphasis mine):

In Class B, Class C, or Class D airspace [controlled airspace] or within the lateral boundaries of the surface area of Class E airspace designated for an airport, the operator obtains prior authorization from the Administrator or designee before operating and complies with all airspace restrictions and prohibitions.

The FAA also has this interactive map showing where airspace restrictions on drones exist.

In the screenshot depicting class B airspace around PHX, it shows that there is a ceiling of 100 feet in the selected square.
Hobbyists cannot currently get permission to fly in controlled airspace due to the absence of LAANC. Is authorization required to fly a drone below 100 feet in this area, or can a hobbyist fly without authorization up to 100 feet since it's within class G airspace and the class B airspace doesn't start until 100 feet? Or, is this location "within the lateral boundaries of the surface area of Class E airspace designated for an airport," requiring authorization for that reason?

https://en.wikipedia.org/wiki/Airspace_class_(United_States)

What a great first question...welcome to the site!

As a drone hobbyist, is flying below the listed FAA UAS ceiling a violation of controlled airspace?

Short answer:
As of now, since the LAANC pre-authorization system is not yet up and running for recreational SUA flyers, any recreational sUAS operation below 9000' MSL in the lower left corner of the grid square highlighted in the question would be violating the applicable rules.  In the rest of the grid square highlighted in the question, recreational sUAS operation from the surface up to 400' AGL violates no rules.
Now read on for more:
In the particular grid square that is highlighted in the question, the LAANC pre-authorization system will only authorize a ceiling of 100'.  But the questioner is mistaken to believe that the floor of the Class B airspace is 100' anywhere in that grid square.
The lower left corner of the grid square highlighted in the question has Class B airspace extending from the surface upwards.  In that airspace, a recreational sUA flyer can not legally fly a drone without prior authorization.  Since the LAANC pre-authorization system is not even operational yet for recreational sUA flyers, to legally fly in any airspace that is Class B at the surface, a rec SUA flyer would have to fly at a "blue dot" fixed site.  "Blue dot" fixed sites are typically prescribed the same ceiling as the ceiling specified for the LAANC grid square in which they are located, which in this case would be 100 feet.  No "blue dot" fixed site currently exists anywhere in the Class-B-to-surface airspace around Phoenix.
Once the LAANC pre-authorization system is up and running for recreation sUA flyers, a rec SUA flyer will be able to use that system to get pre-authorization to fly from the surface up to 100' AGL anywhere in the grid square highlighted in the question.
But does this mean a recreational sUA flyer is limited to a ceiling of 100' AGL if he or she is flying in a part of the grid square highlighted in the question that does NOT have Class B airspace at the surface?
No it does not.
And does the fact that LAANC pre-authorization is not yet available to recreational SUA flyers have any impact on recreational sUA flight in any point within a LAANC grid square if the airspace at that particular point, from the surface up to 400', is NOT Class B, Class C, Class D, Class E airspace that extends down to the surface and is "designated for an airport", or some other kind of restriction such as those shown by the heavy red markings on the LAANC map?
No it does not.
In all but the lower-left corner of the grid square highlighted in the question, the Class B airspace has a floor of 5000' MSL.  Below that is Class E (E5) airspace down to 700' AGL and Class G airspace from 700' AGL down to the surface.  In that airspace, one can legally fly a drone (sUA) up to 400' AGL with no prior authorization of any kind, either as recreational flyer or as a non-recreational flyer, despite being in a LAANC grid square.
VFR sectional chart view, centered on Phoenix: http://vfrmap.com/?type=vfrc&lat=33.434&lon=-112.012&zoom=10
However, if a rec SUA flyer doesn't fully understand the airspace system or how to read a VFR sectional chart, he or she would be wise to stay on the safe side and avoid any operations within any LAANC grid square until the LAANC pre-authorization system becomes operational for sUA flyers, unless he or she is flying at a "blue dot" fixed site.
The phrase "within the lateral boundaries of the surface area of Class E airspace designated for an airport" refers to Class E airspace that extends down ALL THE WAY DOWN TO THE SURFACE.  More specifically, it refers to E2 airspace, but not E3/E3a/E4 airspace.  To read more about this, visit this outside link to a forum for rc flyers-- "Understanding E4 airspace-- prior authorization not required".
No Class E airspace is present at the surface anywhere in the region depicted in the illustration accompanying the question.

Would be interested to know if anyone knows any example of a "blue dot" site where operations are authorized to a ceiling higher than the ceiling given for the LAANC grid square covering that site.  If such a thing exists, I will modify this answer slightly.

It goes without saying that this answer is only meant to address FAA regs and other FAA guidance, not city regulations etc!

Accepting this answer—appreciate the detail, really helped clear up my misunderstanding!

You're welcome -- I think we're going to see some more changes to the drone regs because there is a big problem with regs as they are written-- for more see https://www.rcgroups.com/forums/showpost.php?p=41892815&postcount=7 -- anyway -- future edit to this answer -- to sentence ""Blue dot" fixed sites are typically prescribed the same ceiling as the ceiling specified for the LAANC grid square in which they are located." add "which in this case is 100' AGL."

Comparing that square to the same spot on the Pheonix TAC, to the southwest of the dark blue line is class B from the surface to 9000 MSL. To the northeast is class G from the surface to 700 AGL, class E from 700 AGL to 5000 MSL, and class B from 5000 to 9000 MSL.  There is no "surface area of Class E airspace designated for an airport" here; Winslow-Lindberg (KINW) is the nearest example to Phoenix that I can find.
Since this square contains two (very) different ceilings, they appear to be giving you the more restrictive of the two for the whole square.
However, according to the regulation you quote, it seems like all of the squares inside the dark blue line should have a ceiling of 0 since the class B airspace starts at the surface, yet they do not. Perhaps there is a different regulation that covers those?

When the LAANC is up and running for rec sUA flyers, some flight in class B will be allowed.  A ceiling of 100' rather than 0' is not surprising.  There probably are some blue-dot "fixed sites" located in Class B airspace-- I believe one example is "Electro model fliers 2" in the airspace of MCAS Miramar ( KNKS ).


text:
Is a lower CHT on one cylinder cause for concern?
I have some concerns about the level of maintenance and service on some rental airplanes on an out of town trip.
The first airplane I rented had some misgivings, so I went on a different one today. It was a Cessna 172 and had a Cylinder Head Temperature (CHT) monitor, which I hadn't seen before. So while on an extended leg I fiddled with it. Three of the cylinders where 340-350.  However, cylinder 2 was only 280. That seems like a significant outlier.
Since most rental airplanes don't have a CHT monitor, I don't have experience with what is the normal temperature. Should I be concerned that one cylinder isn't close to the other three?
Below is some information about the airplane and that flight:

Power: 2400 RPM
Altitude: 7500 feet
Oil Quantity: 7 quarts
Oil Pressure: Top of green arc
Oil Temperature: Normal

Airplane was fresh out of a 100-hr maintenance
Anomalous Cylinder: #2

There was some issue with the engine during the 100-hr maintenance which held it up, but was signed off by a mechanic with an IA.
I am unsure about the quality of maintenance service there. We had two flights cancelled in a row because the carburetor  was fine when it was warm, but this cold snap (38°F) is making it hard impossible to start. In addition, there are all sorts of small squawks such as trim that was out of whack etc.
The bottom line is that I am concerned about my safety as probably I will be renting one more time. Is the above mentioned scenario something which could indicate a problem, or more likely something harmless? I have doubts that the maintenance is top quality, but I'm unsure if it's bad enough that I should just opt out.

What power setting? Altitude? OAT? EGT? Cowl flaps, if you have them?

Also, oil pressure and temp? All of these factors can help diagnose engine problems or anomalies in flight.

Added more information.  Oil temp was great about 1/3 into the green, maybe 150-175f.  The oil pressure was slightly disconcerting it was just about the top of the green arc (~85psi).  Power was 2400 RPM (60% base on the POH).  OAT was -9C, at 7500'.  EGT I don't recall the numbers, but I had leaned slightly rich of peak.  No cowl flaps.

@John If I've missed anything, please add. Rollback if you don't like the new form.

I have an 0-470R in a 1969 C182 that has one cylinder (#6 which is the left front of engine looking forward) that has always run cooler at altitude & leaned rich of peak than the rest, especially in cold winter. Compression is good, oil consumption nill, engine runs fine on mag tests. #6 EGT consistently runs 50F in summer to 150F in winter lower than the highest cylinder which is #1. CHTs run 20F in summer to 100F in winter lower than the highest cylinder.

A 60 degree difference in CHT is something worth investigating: It may not be a safety-related issue, but you want to know if it's "normal" for the engine or an indication of a problem.
In order from roughly "Most Benign" to "Worst Case", the CHT difference could be the result of:

A faulty CHT probe
Either the probe is not seated in the cylinder head well properly, or the probe/wiring is defective and causing an inaccurate reading.
Different CHT Probe Types
Spark plug gasket probes can read higher than "normal" cylinder head probes, so if gasket probes were used on cylinders 1, 3, and 4 and a standard bayonet probe used on #2 that would account for the difference.
(I can't see why this would be the case though: usually you have one gasket probe - on the cylinder where the manufacturer's CHT gauge was connected because it's using the normal bayonet probe hole - and bayonet probes in the rest, not the other way around.)
A mixture imbalance
Cylinder #2 is running richer or leaner than the other cylinders.
Since you say the engine is not running rough Cylinder #2 would probably be running rich.  (This is normally something you'd notice with Exhaust Gas Temperature rather than Cylinder Head Temperature.)
You can check for this by watching the engine monitor as you lean the engine: Cylinder #2's EGT will peak at a different time than the rest of the cylinders (early = leaner, late = richer). On fuel-injected engines this can be adjusted for by using tuned injector nozzles. On carbureted engines you just have to live with it - but at least you'll know the cause and be able to determine what "normal" is for this engine.
Fouled/Failed Spark Plug
Easy to check in-flight: Cycle each magneto; If the cylinder dies on one you've found the culprit.
(Something you should probably catch on your preflight mag check too.)
A cooling problem
If the cooling baffles for your engine are worn/damaged/incorrectly positioned you might have anomalous airflow that's directing more cooling air over the #2 cylinder head than the rest of the cylinders.
(Normally you find baffle problems because one or more cylinders are running hot, but cold is possible too.)
A cylinder problem
An exhaust valve that's not fully closing can cause low CHTs - your mechanic can confirm this with a borescope (or a compression test -- they'll hear air escaping through the exhaust if the valve isn't closing).
If this is the case it's something to attend to, because if it's ignored it can lead to an exhaust valve failure, which can ruin your day.

Seems low, but there could be some non-maintenance reasons that a pilot can either see or adjust that have an impact on CHTs. The three most important factors relating to CHT are oil, airflow, and power setting.
Did you check the oil quantity before you flew? It should be in the normal range and of the proper type. You can tell what oil is likely to be in the engine because that'll be the extra quart in the baggage compartment.
Often the front-most cylinders will be the coolest because they are directly exposed to the airflow. For other cylinders, there are rubber air gaskets that direct the airflow over the cylinder heads.  These gaskets can get dislodged and cause assymetrical CHTs. Pitch attitude and cowl flap position also affect airflow.
Power setting and leaning can be adjusted in flight to control CHTs. Lower settings and richer mixtures will show lower temps.


text:
Is it safe to fly with a B737-800? Is it different from a B737 Max 8?
I'm flying from Costa Rica to Chile in November with a B737-800 plane. I'm wondering if this is a different aircraft than the B737 Max 8 or if it's the same?

All B737 Max, as of today 19-Sept-2019, are still grounded and will be for the foreseeable future. So if you are flying in an aircraft, you are guaranteed that it will not be one of those.
As for the underlying question "is it safe to fly in airplane model "X"?" the answer always is that if authorities are allowing it to fly, it is safe to the best of our knowledge.

Yes, it is a different generation of the 737.
The Boeing 737 currently exists in its 4th generation:

Original Series: The first generation first flew in 1967 and consists of the 737-100 and 737-200 models, which differ in fuselage length.
Classic Series: The Classic first flew in 1984 and the main difference is the use of high bypass turbofan engines. It consists of 3 different length variants: 737-300/-400/-500.
Next Generation (NG) Series: The NG first flew in 1997 and consists of 4 different length variants: 737-600/-700/-800/-900. The aircraft you will fly on is from this series, as are most 737s, which are still in use today.
MAX Series: The MAX first flew in 2016 and also consists of 4 different length variants: 737 MAX 7, MAX 8, MAX 9 and MAX 10. As Federico said, all variants of this series are currently grounded because of problems with the newly introduced MCAS.

The 737-800 is not affected by the issues grounding the 737 MAX because the incriminated system (MCAS) does not exist on it.
The 737-800 is part of Boeing's "Next Generation" series.
The 737 Max is much more recent.

A note for the OP: The MAX being "much more recent" does not incriminate the NG series in any way as being old, out-of-date or in any other way unsafe. There are 1000s of NG series aircraft flying with airlines around the world on a daily basis.


text:
Is it necessary to switch from VFR to IFR when using ILS approach?
I have flown at an airport and asked for vectors for an ILS approach in VMC for practice. But the controller refused to give me vectors and told me that I could only have a visual approach.
I got the official answer from our authorities (Ukrainian State Air Traffic Services Enterprise) that it is necessary to switch from VFR to IFR (!) to make ILS approach. But I think that no one can prohibit VFR pilots from using additional guidance, like an ILS.
Here is the answer from UkSATSE:

At your request from 07.05.2021, we would like to inform you that the approach to the instrument landing and guidance for such an approach is performed during the flight according to the rules of instrument flight (IFR). When performing a flight according to the rules of visual flights (VFR) and the need to perform a landing approach for ILS, it is necessary to switch from a flight from VFR to a flight for IFR.

Do you have any idea how we can prove that using an ILS is not prohibited for pilots when flying VFR?

In the USA, I would say: Of course nothing prohibits you from following the ILS guidance on your own. But you only receive "modified IFR separation" if the controller issues a specific clearance to execute the instrument approach procedure. The controller may tell you "VFR practice approach approved, no separation services provided" which means exactly what it sounds like. Or, in busier airspace, they may not permit you to fly even a practice approach, and tell you to go somewhere else. (This would be poor service in my opinion, but you can't expect to fly an ILS into JFK in a C172.)

Are you asking if Ukrainian regulations allow ILS practice approaches under VFR? Or are you asking if a VFR aircraft could technically receive and use the ILS signal?

UkSATSE may not offer “practice” instrument approaches under VFR; they’re not required to. But it’s not clear from their answer if you specifically asked about that; they may have misunderstood you as asking to perform a real ILS approach.

Flying an ILS approach and just using ILS as a guidance are two very different things. The approach comes with many additional things that needs to be followed published on the approach plate.

There is a logical (and legal) fallacy in your last sentence:   You cannot prove a negative, you could only prove that passive reception of ILS signals under VFR is prohibited if you found a rule stating this.  The burden of proof is on anyone stating such a claim to produce the rule, and the rule you quoted doesn’t say this.

It's unclear to me what kind of answer you are looking for here. You already got the officiel answer from the authorities?

Affirm. Our officials in Ukraine wrote me a letter that for using the ILS it is necessary to switch form VFR to IFR.
What does it mean? It means that they prohibited the use of radio beams  as localizer and glide slope from ILS. Funny story. But how can pilots train using ILS? And doesn't it mean that for VOR we need to switch to IFR the same?
I have already written another letter where I was asked to mention a document that prohibits using the ILS approach for VFR. I'm waiting. Thank all of you for helping me with your ideas.

authors: Vladimir F Героям слава